三层材料微悬臂梁模型及其在红外焦平面像元设计中的应用

TRI-LAYER MICROCANTILEVER MODEL AND ITS APPLICATION IN IRFPA PIXEL DESIGN

双材料梁因其良好的热机械特性作为敏感部件被广泛用于热能传感器中.采用微电子工艺实现的双材料梁通常由金属和非金属作为主要功能材料构成,若两层材料之间粘附性差,则需加入一层粘附材料.根据材料力学热应力和弯拉组合理论,建立了用于分析具有中间粘附层的复合双材料(即三层材料)微悬臂梁的关于材料物理参数、结构尺寸与梁受热弯曲产生转角关系模型;利用此模型和工艺中常用材料,研究了三层材料微悬臂梁的材料选取、各层材料厚度匹配等优化设计问题.通过对像元仿真和对硅工艺制造的红外焦平面阵列(IRFPA)芯片进行测试,验证了模型的正确、合理和适用性.

Bi-material cantilever is an important element in a heat energy sensor for its thermal-mechanical character. The cantilever based on silicon process is usually made of metal and non-metal films. To improve the reliability of the cantilever, an adhesion layer is often needed between two films which do not adhere steadily each other. For analyzing bi-material structure with an abhesive layer in between, according to the theories of thermal stress and combined deformation on mechanics of materials, a tri-layer material cantilever model was set up related to the physics properties of materials, the struc- ture dimension of cantilever, and the tilt angle caused by thermal stress. The material selection, the thickness, and the thickness ratio determination of a tri-layer material cantilever were analyzed by this model. Based on silicon process an optic readout infrared focal plane array（IRFPA） was designed, fabricated, and tested. The results show that the model is practi- cal and accurate enough. The model was also verified by a finite element simulation.